1. Field Of The Invention
The present invention relates to a method and associated apparatus for automatically inspecting containers in order to confirm the presence of adhesive material at desired locations.
2. Description Of The Prior Art
It has been known to manufacture containers having a generally cup-like base portion which may be made of polyethylene having an annular base wall and an annular side wall extending upwardly and outwardly therefrom. By providing discrete locations with a suitable hot melt adhesive, a bottle composed of a suitable material such as polyethylene terephthalate may be secured to the base portion. In this type of assembly the base provides an economically feasible inexpensive base member and the bottle or other container may be made of an inexpensive relatively thin material depending upon whether the contents will be pressurized or not. The lower portion of the container is generally hemispherical as this is an efficient and economical way to manufacture a container for pressurized contents. It is apparent that an important aspect of this type of a container assembly is that the desired amount of adhesive be provided at the desired number of locations in order to create an effective bond between the base and the bottle.
One of the problems in connection with this type of container is that occasionally adhesive spray nozzles which apply adhesive to the locations on the base will clog and result in the base not receiving the desired adhesive at the desired spots. For example, if it is determined that three adhesive spots are required in order to securely bond the base to the overlying container, frequently a manufacturer will employ a fourth adhesive spot in order to enhance the likelihood that at least three adhesive spots will be present. While this does, in fact, minimize the risk of there not being the desired minimum of three adhesive spots, for example, it is wasteful of adhesive material.
It has also been known in a different environment that where a coating is provided with multiple layers of substances having different luminescent properties, telescopic examination of the materials may be employed. See U.S. Pat. No. 4,460,274.
There remains a very real and substantial need for inspection apparatus which can effectively and accurately determine whether adhesive is located at the desired minimum number of locations required in order to secure a container base to an overlying container.